Mitochondria influence CDR1 efflux pump activity, Hog1-mediated oxidative stress pathway, iron homeostasis, and ergosterol levels in Candida albicans

Antimicrob Agents Chemother. 2013 Nov;57(11):5580-99. doi: 10.1128/AAC.00889-13. Epub 2013 Aug 26.


Mitochondrial dysfunction in Candida albicans is known to be associated with drug susceptibility, cell wall integrity, phospholipid homeostasis, and virulence. In this study, we deleted CaFZO1, a key component required during biogenesis of functional mitochondria. Cells with FZO1 deleted displayed fragmented mitochondria, mitochondrial genome loss, and reduced mitochondrial membrane potential and were rendered sensitive to azoles and peroxide. In order to understand the cellular response to dysfunctional mitochondria, genome-wide expression profiling of fzo1Δ/Δ cells was performed. Our results show that the increased susceptibility to azoles was likely due to reduced efflux activity of CDR efflux pumps, caused by the missorting of Cdr1p into the vacuole. In addition, fzo1Δ/Δ cells showed upregulation of genes involved in iron assimilation, in iron-sufficient conditions, characteristic of iron-starved cells. One of the consequent effects was downregulation of genes of the ergosterol biosynthesis pathway with a commensurate decrease in cellular ergosterol levels. We therefore connect deregulated iron metabolism to ergosterol biosynthesis pathway in response to dysfunctional mitochondria. Impaired activation of the Hog1 pathway in the mutant was the basis for increased susceptibility to peroxide and increase in reactive oxygen species, indicating the importance of functional mitochondria in controlling Hog1-mediated oxidative stress response. Mitochondrial phospholipid levels were also altered as indicated by an increase in phosphatidylserine and phosphatidylethanolamine and decrease in phosphatidylcholine in fzo1Δ/Δ cells. Collectively, these findings reinforce the connection between functional mitochondria and azole tolerance, oxidant-mediated stress, and iron homeostasis in C. albicans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antifungal Agents / pharmacology
  • Azoles / pharmacology
  • Candida albicans / drug effects
  • Candida albicans / genetics*
  • Candida albicans / metabolism
  • Drug Resistance, Fungal / drug effects
  • Drug Resistance, Fungal / genetics
  • Ergosterol / metabolism*
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • GTP Phosphohydrolases / deficiency
  • GTP Phosphohydrolases / genetics
  • Gene Deletion
  • Gene Expression Profiling
  • Gene Expression Regulation, Fungal*
  • Genome, Mitochondrial
  • Homeostasis / genetics
  • Iron / metabolism*
  • Membrane Potential, Mitochondrial / drug effects
  • Membrane Transport Proteins / genetics*
  • Membrane Transport Proteins / metabolism
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Mitochondria / pathology
  • Mitochondrial Proteins / deficiency
  • Mitochondrial Proteins / genetics
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism
  • Oxidative Stress
  • Signal Transduction


  • Antifungal Agents
  • Azoles
  • CDR1 protein, Candida albicans
  • Fungal Proteins
  • Membrane Transport Proteins
  • Mitochondrial Proteins
  • Iron
  • Mitogen-Activated Protein Kinases
  • GTP Phosphohydrolases
  • Ergosterol